scholarly journals Intracellular injection of phospholipids directly alters exocytosis and the fraction of chemical release in chromaffin cells as measured by nano-electrochemistry

2020 ◽  
Vol 11 (43) ◽  
pp. 11869-11876
Author(s):  
Mohaddeseh Aref ◽  
Elias Ranjbari ◽  
Armaghan Romiani ◽  
Andrew G. Ewing
Keyword(s):  
Chromaffin Cells ◽  
Secretory Cells ◽  
Intracellular Injection ◽  
Chemical Release ◽  
Intracellular Vesicle ◽  
Electrochemical Cytometry

Amperometry and intracellular vesicle impact electrochemical cytometry with nanotip electrodes were used to monitor the effects on exocytosis and vesicular storage after nano-injection of phospholipids with different geometries into secretory cells.

The cytoskeleton as a barrier to exocytosis in secretory cells

1988 ◽  
Vol 139 (1) ◽  
pp. 253-266 ◽  
Author(s):  
D. Aunis ◽  
M. F. Bader
Keyword(s):  
Chromaffin Cells ◽  
Binding Proteins ◽  
Secretory Granules ◽  
Actin Binding ◽  
Bacterial Toxin ◽  
Secretory Cells ◽  
Free Access ◽  
Actin Binding Proteins ◽  
Permeabilized Cells ◽  
Cytoskeletal Network

Chromaffin cells of the adrenal medulla synthesize, store and secrete catecholamines. These cells contain numerous electron-dense secretory granules which discharge their contents into the extracellular space by exocytosis. The subplasmalemmal area of the chromaffin cell is characterized by the presence of a highly organized cytoskeletal network. F-Actin seems to be exclusively localized in this area and together with specific actin-binding proteins forms a dense viscoelastic gel; fodrin, vinculin and caldesmon, three actin cross-linking proteins, and gelsolin, an actin-severing protein, are found in this subplasmalemmal region. Since fodrin-, caldesmon- and alpha-actinin-binding sites exist on secretory granule membranes, actin filaments can also link secretory granules. Chromaffin granules can be entrapped in this subplasmalemmal lattice and thus the cytoskeleton acts as a barrier preventing exocytosis. When cells are stimulated, molecular rearrangements of the subplasmalemmal cytoskeleton take place: F-actin depolymerizes and fodrin reorganizes into patches. In addition, introduction of monospecific antifodrin immunoglobulins into digitonin-permeabilized cells blocks exocytosis, demonstrating the crucial role of this actin-binding protein. In bacterial toxin-permeabilized chromaffin cells, experiments using actin-perturbing agents such as cytochalasin D and DNAase I suggest that exocytosis is in part controlled by the cytoskeleton. The intracellular signal governing the cytoskeletal reorganization (associated with exocytosis) is calcium. Calcium inhibits some and activates other actin-binding proteins and consequently causes dissolution of the subplasmalemmal cytoskeleton. This dissolution of cytoskeletal filaments should result in granule detachment and permit granules free access to exocytotic sites on the plasma membrane.

scholarly journals Secretory cell actin-binding proteins: identification of a gelsolin-like protein in chromaffin cells.

1986 ◽  
Vol 102 (2) ◽  
pp. 636-646 ◽  
Author(s):  
M F Bader ◽  
J M Trifaró ◽  
O K Langley ◽  
D Thiersé ◽  
D Aunis
Keyword(s):  
Adrenal Medulla ◽  
Chromaffin Cells ◽  
Binding Proteins ◽  
Binding Protein ◽  
Actin Binding ◽  
Secretory Process ◽  
Secretory Cells ◽  
Breakdown Product ◽  
Actin Binding Proteins ◽  
Actin Binding Protein

Chromaffin cells, secretory cells of the adrenal medulla, have been shown to contain actin and other contractile proteins, which might be involved in the secretory process. Actin and Ca++-sensitive actin-binding proteins were purified from bovine adrenal medulla on affinity columns using DNase-I as a ligand. Buffers that contained decreasing Ca++ concentrations were used to elute three major proteins of 93, 91, and 85 kD. The bulk of the actin was eluted with guanidine-HCl buffer plus some 93- and 91-kD proteins. These Ca++-sensitive regulatory proteins were shown to inhibit the gelation of actin using the low-shear falling ball viscometer and by electron microscopy. Actin filaments were found to be shortened by fragmentation. Using antibody raised against rabbit lung macrophage gelsolin, proteolytic digestion with Staphylococcus V8 protease and two-dimensional gel electrophoresis, the 91-kD actin-binding protein was shown to be a gelsolin-like protein. The 93-kD actin-binding protein also showed cross-reactivity with anti-gelsolin antibody, similar peptide maps, and a basic-shift in pHi indicating that this 93-kD protein is a brevin-like protein, derived from blood present abundantly in adrenal medulla. Purification from isolated chromaffin cells demonstrated the presence of 91- and 85-kD proteins, whereas the 93-kD protein was hardly detectable. The 85-kD protein is not a breakdown product of brevin-like or gelsolin-like proteins. It did not cross-react with anti-gelsolin antibody and showed a very different peptide map after mild digestion with V8 protease. Antibodies were raised against the 93- and 91-kD actin-binding proteins and the 85-kD actin-binding protein. Antibody against the 85-kD protein did not cross-react with 93- and 91-kD proteins and vice versa. In vivo, the cytoskeleton organization of chromaffin secretory cells is not known, but appears to be under the control of the intracellular concentration of free calcium. The ability of calcium to activate the gelsolin-like protein, and as shown elsewhere to alter fodrin localization, provides a mechanism for gel-sol transition that might be essential for granule movement and membrane-membrane interactions involved in the secretory process.

scholarly journals Stimulus-secretion coupling in excitable cells: a central role for calcium

1993 ◽  
Vol 184 (1) ◽  
pp. 183-196 ◽  
Author(s):  
T. R. Cheek ◽  
V. A. Barry
Keyword(s):  
Patch Clamp ◽  
Chromaffin Cells ◽  
Calcium Concentration ◽  
Flash Photolysis ◽  
Secretory Cells ◽  
Adrenal Chromaffin Cells ◽  
Excitable Cells ◽  
Stimulus Secretion Coupling ◽  
Adrenal Chromaffin ◽  
Dependent Processes

Secretion of vesicular contents by exocytosis is a common feature of neuroendocrine secretory cells such as adrenal chromaffin cells and PC12 cells. Although it is clear that in these cells an elevation in intracellular calcium concentration, [Ca2+]i, is the triggering event that induces secretion, recent studies using video-imaging, patch-clamp and flash photolysis techniques have all indicated that the Ca2+ signal that triggers secretion is in fact very complex, with the subcellular distribution of Ca2+ being of particular importance along with the magnitude of the rise. It has become evident that Ca2+ signals with different spatial profiles can be triggered in the same cell by a given stimulus, depending upon the nature of the Ca2+ signalling pathway activated, and that this ability to be able to vary the method of delivery of Ca2+ into the cell is important physiologically, because it provides a means of obtaining differential activation of Ca(2+)-dependent processes.

scholarly journals Combined Amperometry and Electrochemical Cytometry Reveal Differential Effects of Cocaine and Methylphenidate on Exocytosis and the Fraction of Chemical Release

2019 ◽  
Vol 131 (13) ◽  
pp. 4282-4286 ◽  
Author(s):  
Wanying Zhu ◽  
Chaoyi Gu ◽  
Johan Dunevall ◽  
Lin Ren ◽  
Xuemin Zhou ◽  
...  
Keyword(s):  
Differential Effects ◽  
Chemical Release ◽  
Electrochemical Cytometry

scholarly journals Effect of taxol on secretory cells: functional, morphological, and electrophysiological correlates.

1985 ◽  
Vol 100 (6) ◽  
pp. 1863-1874 ◽  
Author(s):  
J Thuret-Carnahan ◽  
J L Bossu ◽  
A Feltz ◽  
K Langley ◽  
D Aunis
Keyword(s):  
Chromaffin Cells ◽  
Secretory Activity ◽  
Ultrastructural Level ◽  
Secretory Cells ◽  
Patch Clamp Technique ◽  
Cell Axis ◽  
Ultrastructural Studies ◽  
Microtubule Polymerization ◽  
Long Term Effect

The effect of 0.5-1.0 microM taxol, a potent promoter of microtubule polymerization in vitro, was studied on the secretory activity of chromaffin cells of the adrenal medulla. Taxol was found to have a dual effect: the long-term effect (after a 1-h incubation) of taxol was to induce almost complete inhibition of catecholamine release, whereas after a short incubation (10 min) a massive, nicotine-independent release of catecholamine was produced. From results obtained using the patch-clamp technique to study the Ca++-dependent K+ channels (Ic channels), it was possible to conclude that taxol probably provokes an augmentation of free [Ca++]i in the cytoplasm, values increasing from 10(-8) M at rest to several 10(-7) M. The increased spontaneous release of stored neurohormones and the increased frequency of opening of Ic channels occur simultaneously and could both originate from a rise of [Ca++]i upon taxol addition. Immunofluorescence and ultrastructural studies showed that 13-h taxol treatment of chromaffin cells led to a different distribution of secretory organelles, and also to microtubule reorganization. In treated cells, microtubules were found to form bundles beneath the cell membrane and, at the ultrastructural level, to be packed along the cell axis. It is concluded that in addition to its action on microtubules, the antitumor drug taxol has side effects on the cell secretory activity, one of them being to modify free [Ca++]i.

The 1989 Upjohn Award Lecture. Cellular and molecular mechanisms in hormone and neurotransmitter secretion

1990 ◽  
Vol 68 (1) ◽  
pp. 1-16 ◽  
Author(s):  
José-María Trifaró
Keyword(s):  
Adrenal Medulla ◽  
Chromaffin Cells ◽  
Secretory Cell ◽  
Secretory Granules ◽  
Secretory Process ◽  
Secretory Cells ◽  
Secretory Vesicles ◽  
Cell Secretion ◽  
Chromaffin Granule ◽  
Calmodulin Binding

Studies on adrenal medulla have had an important influence on the development of a variety of biological concepts, not only within the area of endocrinology, but also in the areas of chemical neurotransmission and secretion in general. The adrenal medulla chromaffin cells are derived embryologically from the neural crest, sharing a common origin with sympathetic neurons and common subcellular features with many endocrine cells. One such feature is the storage of secretory products in membrane-bound organelles, the secretory granules. Secretory cells with these characteristics have been named paraneurons, a term that embraces cells generally and traditionally not considered as neurons, and yet should be regarded as relatives of neurons on the basis of their structure, function, and metabolism. Many of the studies carried out in the past to understand the secretory process have employed perfused adrenal glands. Although this technique has provided very useful information regarding secretion, it did not allow the study of the cellular events involved in the secretory process. To obtain further information on cell secretion, several laboratories including our own have published methods for the isolation and culture of chromaffin cells. The cultured chromaffin cells have shown themselves to be one of the most useful systems developed for the study of the neuroendocrine functions of paraneurons. Studies on cultured chromaffin cells have provided important information on secretory cell cytoskeleton: a group of proteins, some of them previously known from studies on muscle, which form a cytoplasmic network in all non-muscle cells including secretory cells. Immunohistochemical studies have shown at least three types of filament systems: microfilaments, microtubules, and intermediate filaments. In addition, a large variety of cytoskeleton-associated proteins have been characterized. Chromaffin cells are among those non-muscle cells from which cytoskeleton proteins have been isolated and characterized. Owing to similarities between "stimulus–secretion coupling" and "excitation–contraction coupling" in muscle, it has been proposed that the secretory process might be mediated by contractile elements either associated with secretory vesicles or present elsewhere in the secretory cell. Cytoskeletal proteins (actin, myosin, α-actinin, fodrin, tubulin, and neurofilament subunits) and their regulatory proteins (calmodulin, gelsolin) have been isolated from chromaffin cells and characterized. Their physicochemical proteins have been studied and their cellular localizations have been revealed by biochemical, immunocytochemical, and ultrastructural techniques. α-Actinin and fodrin are components of chromaffin granule membranes and some of the cell actin co-purified with secretory granules. Actin forms a network of microfilaments in the subplasmalemma region. This network of filaments is cross-linked and stabilized by several proteins as well as secretory vesicles. Gelsolin, a Ca2+-dependent actin filament severing protein seems to control the length of the actin filaments, thus playing an important role in the regulation of cytoplasm viscosity. Calmodulin also seems to be involved in secretion. Trifluoperazine, a calmodulin antagonist, blocks stimulation-induced hormone release from chromaffin cells at a step distal from calcium entry. High affinity calmodulin binding sites are present in chromaffin granule membranes, and the calmodulin binding proteins of these membranes have been characterized. Furthermore, microinjection of calmodulin antibodies into chromaffin cells blocks hormone output in response to cell stimulation. In view of the above findings, the possible roles of contractile proteins and calmodulin in cell secretion are discussed.Key words: secretion, cytoskeleton, paraneuron, calmodulin, cytosol viscosity.

The ultrastructure of acinar cells in the external orbital gland of young and old male rats

1978 ◽  
Vol 36 (2) ◽  
pp. 276-277
Author(s):  
R. Carriere
Keyword(s):  
Young Adulthood ◽  
Acinar Cells ◽  
Cell Number ◽  
Male Rats ◽  
Polyploid Cell ◽  
Secretory Cells ◽  
Age Changes ◽  
Albino Rat ◽  
Golgi Membranes ◽  
Diploid Cells

The external orbital gland of the albino rat exhibits both sexual dimorphism and histological age changes. In males, many cells attain a remarkable degree of polyploidy and an increase of polyploid cell number constitutes the major age change until young adulthood. The acini of young adults have a small lumen and are composed of tall serous cells. Subsequently, many acini acquire a larger lumen with an irregular outline while numerous vacuoles accumulate throughout the secretory cells. At the same time, vesicular acini with a large lumen surrounded by pale-staining low cuboidal diploid cells begin to appear and their number increases throughout old age. The fine structure of external orbital glands from both sexes has been explored and in considering acinar cells from males, emphasis was given to the form of the Golgi membranes and to nuclear infoldings of cytoplasmic constituents.

Sign in / Sign up

Export Citation Format

Share Document